Descartes' Modal Metaphysics

Descartes sometimes speaks of things that have possible existence, in
addition to speaking of things as having actual existence. He also
speaks of eternal and necessary truths that God could nonetheless make
false. One of the interpretive projects that is inspired by
Descartes' claims about possibility and necessity is the construction
of a general Cartesian theory of modality. Any such theory would of
course need to be sensitive to what Descartes says about possibility
and necessity, but it must also be sensitive to his larger
metaphysical system.

Though Descartes makes a number of claims about possibilities and
necessities, not all of them are to be considered in determining his
views on modality if we take seriously his view that when doing
metaphysics we ought not affirm what we do not clearly and distinctly
perceive. Descartes reveals his commitment to this view in a number of
places:

I should like you to remember here that, in matters which
may be embraced by the will, I made a very careful distinction between
the conduct of life and the contemplation of the truth. As far as the
conduct of life is concerned, I am very far from thinking that we
should assent only to what is clearly perceived. …But when we
are dealing solely with the contemplation of the truth, surely no one
has ever denied that we should refrain from giving assent to matters
which we do not perceive with sufficient
distinctness.[1]

If Descartes holds that when doing strict metaphysics we ought not
speak of what we do not clearly and distinctly perceive, a general
Cartesian theory of modality should not be sensitive to claims about
possibilities or necessities that are confused.

One reason why it is important to highlight the distinction between
modal claims that are confused and modal claims that are not is that
there are many modal claims that we might want to give a rigorous
analysis but that Descartes would not. He will not construct his
theory of modality around modal claims that his system entails are
confused, and so the theory that he offers will not necessarily square
with all of the modal claims that we would advance pre-reflectively.
For example, we might observe a blue table in front of us and put
forward the claim that it is possible that the table not be blue and
that it could have been black. Descartes himself is going to be
careful about accepting such a claim at face-value. He subscribes to
the view that strictly speaking our senses “provide only very
obscure information” (The Sixth Meditation, AT 7:84, CSM 2:58)
about the bodies located outside of us. Our “knowledge of the
truth of such things [located outside of us] seems to belong to the
mind alone, not to the combination of mind and body”
(ibid., AT 7:82–83, CSM 2:57), but the mind on its own
knows such qualities of bodies as their extendedness and flexibility
(The Second Meditation, AT 7:30–31, CSM 2:20). The certainty
that we seek in metaphysical inquiry “occurs in the clear
perceptions of the intellect and nowhere else” (Second
Replies, AT 7:145, CSM 2:104). Returning now to the claim that
it is possible that a given table not be blue and that it could have
been black, we need to keep in mind (for example) that on Descartes'
view colors are not in objects in the way that we normally imagine
them to be (Principles of Philosophy I:68, AT 8A:33, CSM
1:217). We might also advance the claim that our blue table could
occupy a different position in empty space, or the claim that it could
begin to move without being pushed into motion by a cause. The first
claim supposes what Descartes denies — that there is empty space
(Principles II:10–12, AT 8A:45–47, CSM
1:226–28) — and the second contradicts a Cartesian law of
motion that falls immediately out of our idea of God
(Principles II:36–37, AT 8A:61–63, CSM
1:240–41; Nadler 1987). However the debate is resolved on these
important systematic issues, it is important to keep in mind that
Descartes' theory of modality will be somewhat
circumscribed.[2]

Another reason why it is important to highlight the distinction
between modal claims that are confused and modal claims that are not
is that in what is perhaps his most important and influential
philosophical work — Meditations on First Philosophy —
Descartes often advances a claim that in the final analysis (and that
upon further reflection) he will reject. For example, he says that
what we know best we know either from or through the senses (First
Meditation, AT 7:18, CSM 2:17); that we should use imagination to get
to know our minds better (Second Meditation, AT 7:27, CSM 2:18); that
general perceptions are apt to be more confused than particular ones
(ibid., AT 7:30, CSM 2:20); that bodies really have qualities like
color and taste and sound (ibid.) and heat (Third Meditation, AT 7:41,
43–44, CSM 2:28, 30–31); and that the appropriate way to inquire into
whether or not the works of God are perfect is to examine the universe
in its entirety (The Fourth Meditation, AT 7:55–56, CSM 2:38–39).
Descartes thinks that upon further reflection we can recognize that
what is known best is known by purely mental scrutiny (Second
Meditation, AT 7:31, CSM 2:21); that general perceptions are more
clear than perceptions of particulars (ibid.); that color and taste
and sound and heat are not in bodies in anything like the way that we
imagine (Sixth Meditation, AT 7:81–83, CSM
2:56–58; Principles IV:198, AT 8A:322–23, CSM 1:285); and
that things are good by virtue of the fact that God wills them
(Sixth Replies, AT 7:431–36, CSM 2:291–94).

Descartes advances a number of claims that are false in
the Meditations, but he does this for good reason. He is
writing in the voice of a meditator who at the start of inquiry is not
yet a Cartesian and who in the course of inquiry is expressing views
that seem to him to be true from his non-Cartesian point-of-view. The
meditator will express and evaluate these views and see for himself
how they collapse on their own weight.

It might seem surprising that as a philosopher Descartes ever flirts
with confusions at all. When he does so he is just employing
his analytic method — what he calls the “best and
truest method of instruction…” (Second Replies,
AT 7:156, CSM 2:111). Descartes does not hide that he sometimes makes
claims early in the Meditations that from a later and more
sophisticated point of view he will retract. He says,

The analytic style of writing that I adopted there [in the
Meditations] allows us from time to time to make certain
assumptions that have not yet been thoroughly examined; and this comes
out in the First Meditation where I made many assumptions which I
proceeded to refute in subsequent
Meditations.[3]

Descartes advances these claims because he is trying to teach his
metaphysics and because he thinks that his readers will not be in a
position to grasp that metaphysics if he only makes claims that are
true.[4]
Reflecting the epistemic individualism that is common in 17th-Century
Philosophy, Descartes insists that we should not accept a view until
we see its truth for ourselves (Appendix to Fifth Replies, AT
9A:208, CSM 2:272–73). But he also holds that at the start of inquiry
our conceptions and commitments are way off. Most of us are inclined
to affirm that what we know best we know through the senses, along
with the other falsities already mentioned, but in addition: our
conceptions of mind and God represent mind and God as sensible when
they are not; we think and speak by way of terms that we do not
understand or that may have no corresponding idea; and what we take to
be the paradigm of a distinct perception is hardly distinct at
all.[5] We take in
information against the background of our current commitments and
conceptions, and so are primed to reject what conflicts with
them.[6] When we
work through the
Meditations from the first-person point-of-view, we accept or
reject things when we see for ourselves that they are to be accepted
or rejected, but until our intellects are emended we do not have the
best perspective from which to see the truth.

For example, in the First Meditation Descartes entertains a number
of possibilities that suggest that we might be mistaken about results
that are perfectly evident to us. One such possibility is that we have
been created by a supremely good God but that, for reasons unbeknownst
to us, our nature is such that we “go wrong every time [we] add
two and three or count the sides of a square, or in some even simpler
matter” (AT 7:21, CSM 2:14). Another is that we have not been
created by God but have “arrived at [our] present state by fate
or chance or a continuous chain of events” (AT 7:21, CSM
2:14). A third is that we are constantly deceived by a malicious demon
(AT 7:22, CSM 2:15). Descartes mentions all of these possibilities to
set up his Third Meditation point that until we know what made our
minds, we are not in a position to trust them and so not in a position
to know anything at all (AT 7:36, CSM 2:25). None of these is an
actual possibility, though Descartes allows that we may not appreciate
this until later:

[Voetius claims that in my philosophy] “God is
thought of as a deceiver.” This is foolish. Although in my First
Meditation I did speak of a supremely powerful deceiver, the
conception there was in no way of the true God, since, as he himself
says, it is impossible that the true God should be a deceiver. But if
is asked how he knows that this is impossible, he must answer that he
knows it from the fact that it implies a contradiction — that is, it
cannot be conceived. (“Letter to Voetius,” May 1643, AT
8B:60)

Descartes of course holds that upon reflection it is obvious that God
is a necessary existent, and a necessary existent who cannot deceive
(The Fifth Meditation, AT 7:66–70). We might have thought otherwise
at the start of inquiry, before we had carefully unpacked and examined
our concepts, and when we were not yet putting forward the a priori
non-sensory claims that are the only suitable premises for use in
metaphysical arguments. As often happens in philosophy, we come to
recognize that there are things that seem clear to us before we have
thought them through and that the reason why they seemed clear was
that we hadn't thought them through. As Descartes himself writes,

In order to philosophize seriously and search out the
truth about the things that are capable of being known, we must first
of all lay aside all our preconceived opinions, or at least we must
take the greatest care not to put our trust in any of the opinions
accepted by us in the past until we have first scrutinized them afresh
and confirmed their truth. Next, we must give our attention in an
orderly way to the notions that we have within us, and we must judge
to be true all and only those whose truth we clearly and distinctly
recognize when we attend to them in this way. …When we contrast
all this knowledge with the confused thoughts we had before, we will
acquire the habit of forming clear and distinct concepts of all the
things that can be known. These few instructions seem to me to
contain the most important principles of human
knowledge. (Principles I:75, AT 8A:38–9, CSM
1:221)

When we construct arguments on the basis of basic a priori
principles of metaphysics — what Descartes calls “primary
notions” (Second Replies, AT 7:145–46, CSM
2:104; Principles I:50, AT 8A:23–24, CSM 1:209) —
and not the non a priori premises that constitute much of the early
thinking of Descartes' meditator, we recognize that God is a necessary
existent who cannot deceive and also that He is the independent and
supreme creator of all reality, both possible and actual (“To
[Mesland], 2 May 1644,” AT 4:118–19, CSMK 235; “To
[Mersenne], 27 May 1630,” AT 1:152, CSMK 25; Third Meditation,
AT 7:45, CSM 2:31). We know on a priori grounds that the skeptical
possibilities of the First Meditation do not exist. It turns out, upon
reflection, that God did not create them. This is not to say that the
possibilities exist but that they do not obtain or that God did not
actualize them, but instead to say that the possibilities themselves
are not real — that they have no ontological status and so are
not really possibilities at all. God did not create the possibility
that we exist with minds that might be certain of things that are
false; He did not create the possibility that we evolved from chance;
He did not create the possibility of an evil demon. None of these
possibilities exists automatically, and they do not exist just because
the cognitive deliverances of the First Meditation meditator tell us
that they do. When we (or the meditator) postulated their existence in
the First Meditation, we were being hasty, and all that we had to go
on was our confused conceptions.

Descartes is very explicit about the importance of employing (what
some might regard as a not completely honest) pedagogical method. In
order to maneuver his readers into a position in which they
are able to understand his metaphysics, he needs to
help them to clear up their ideas. If he simply tells us his view, we
will hear it in terms of the confused ideas that (on his view) it is
imperative we discard. The view that we would walk away with would not
be Descartes' view but something else. Descartes therefore opts for a
special strategy for presenting his metaphysics: he puts things in
terms of the confusions that we understand, otherwise we will not
understand him. If we object (as does Gassendi) to this kind of
maneuver, Descartes insists that under the circumstances it is only
appropriate. He says,

A philosopher would be no more surprised at such
suppositions of falsity than he would be if, in order to straighten out
a curved stick, we bent it round in the opposite direction. The
philosopher knows that it is often useful to assume falsehoods instead
of truths in this way in order to shed light on the truth…
(Fifth Replies, AT 7:349–50, CSM 2:242).

Descartes does not see anything objectionable in guiding us to truth
by way of conceptions that are false or incoherent. Instead, he is
providing a service:

[T]ake the case of someone who imagines a deceiving god —
even the true God, but not yet clearly enough known to himself or to
the others for whom he frames his hypothesis. Let us suppose that he
does not misuse this fiction for the evil purpose of persuading others
to believe something false of the Godhead, but uses it only to
enlighten the intellect, and bring greater knowledge of God's nature
to himself and to others. Such a person is in no way sinning in order
that good may come. There is no malice at all in his action; he does
something which is good in itself, and no one can rebuke him for it
except slanderously. (“To Buitendijck 1643,” AT 4:64, CSMK
230)

The possibilities that Descartes mentions early in the
Meditations are not a part of his ontology. When he talks
about these, he is not interested in truth but, rather, in helping his
reader to move through and past
confusion.[7]
Unless we are going to saddle Descartes
with the view that it really is possible that our minds are radically
defective and that we ought to go on reasoning anyway, we should
conclude that Descartes holds that the possibilities of the First
Meditation were never created and that hence they are nothing at
all.

Descartes is infamous for his doctrine of the creation of the
eternal truths:

You ask me by what kind of causality God established the
eternal truths. I reply: by the same kind of causality as he created
all things, that is to say, as their efficient and total cause. (“To
[Mersenne], 27 May 1630,” AT 1:152, CSMK 25)

On the surface the position is baffling, especially when considered in
conjunction with Descartes' view that God is omnipotent. The author of
Fifth Objections, Pierre Gassendi, complained that the view is very
difficult to conceive. Descartes' reply is interesting:

You say that you think it is ‘very hard’ to
propose that there is anything immutable and eternal apart from God.
You would be right to think this if I was talking about existing
things, or if I was proposing something as immutable in the sense that
its immutability was independent of God. But just as the poets suppose
that the Fates were originally established by Jupiter, but that after
they were established he bound himself to abide by them, so I do not
think that the essences of things, and the mathematical truths which
we can know concerning them, are independent of God. Nevertheless I do
think that they are immutable and eternal, since the will and decree
of God willed and decreed that they should be so. Whether you think
this is hard or easy to accept, it is enough for me that it is
true. (Fifth Replies, AT 7:380, CSM 2:261)

Descartes holds that each and every thing depends on God for its
existence and that, as things, eternal truths depend on God as well.
One of Gassendi's worries is that if God can do anything and thus can
alter any item that He creates, nothing that He creates is
immutable.

Another reason that Descartes' view is difficult to conceive is that
Descartes takes eternal truths to be necessary. That is, it is
difficult to conceive how eternal truths could be necessary if they
were created by a free act of God. Descartes is clear that the
eternal truths are necessary: he says that “the necessity of
these truths does not surpass our knowledge” (“To
Mersenne, 6 May 1630,” AT 1:150, CSMK 25). If eternal truths
are necessary, however, it should not be the case that they could have
been otherwise. Yet Descartes' commitment to divine omnipotence
appears to commit him to this view:

You ask what necessitated God to create these truths; and
I reply that he was free to make it not true that all the radii of the
circle are equal — just as free as he was not to create the
world. And it is certain that these truths are no more necessarily
attached to his essence than are other created things. (“To
[Mersenne], 27 May 1630,” AT 1:152, CSMK 25)

It appears that something in Descartes' comments about the eternal
truths has to give. It might be that, since Descartes is clearly not
prepared to adjust his commitment to divine omnipotence, he instead
abandons his view that they are
necessary.[8]
On this interpretation, developed and defended by Harry Frankfurt,
all eternal truths are inherently contingent because they could have
been false, and they could have been false because God could have made
their contradictories true. Frankfurt's interpretation is motivated
not only by Descartes' commitment to divine omnipotence; there are
also some texts:

… God cannot have been determined to make it true
that contradictories cannot be true together, and therefore… he
could have done the
opposite.[9]

I do not think that we should ever say of anything that it cannot be
brought about by God. For since every basis of truth and goodness
depends on his omnipotence, I would not dare to say that God cannot
make a mountain without a valley, or bring it about that 1 and 2 are
not 3.[10]

If Frankfurt is right, Cartesian eternal truths are not really
necessary; they “are inherently as contingent as any other
propositions” (42). They may appear to be necessary to our
rational faculties, but this is just a function of the makeup of our
rational faculties and not of the necessity of the truths themselves.
Frankfurt then argues more generally that Descartes holds that for all
we know our rational faculties may be wrong about other things as
well. There is a way that reality appears from the viewpoint of the
clearest of human reasoning, and the best that we can do as rational
agents is to take up that viewpoint. But we can never get outside of
it to see how things are
absolutely.[11]

If Descartes holds that eternal truths are necessary in any robust
sense, Frankfurt's view has an obvious drawback. It also suffers from
the problem that it cannot be formulated without supposing that
Descartes would allow that human minds can know that there is a
perspective from which eternal truths can be seen to be contingent,
but an important component of Frankfurt's view is the thesis that
Descartes thinks that it is part of the structure of a human mind to
regard eternal truths as wholly necessary. The most serious drawback
for Frankfurt's view, however, is that it is self-contradictory in
postulating that, according to Descartes, we cannot make claims about
what reality is like absolutely. The central tenet that is driving
Frankfurt's interpretation is that on Descartes' view God is
omnipotent in the sense that He can do anything imaginable. He
created the eternal truths that are in fact with us, and He could have
done otherwise. All of these are claims about God and what God is
like absolutely.

An alternative view (developed and defended by
Edwin Curley) is that Descartes holds that eternal truths are
necessary, but that they are not necessarily so. On this reading,
Descartes' view involves iterated modalities: a number of truths are
possibly necessary, but God chooses only some of these possibilities
to be the actual necessary
truths.[12]
One of
the passages that supports such a reading is from the already-cited
letter to Mesland:

And even if God has willed that some truths should be
necessary, this does not mean that he willed them necessarily; for it
is one thing to will that they be necessary, and quite another to will
this necessarily, or to be necessitated to will
it.[13]

On Curley's reading, Descartes secures the necessity of eternal truths
by arguing that God willed them to be necessary, and hence it can be
said that it is false that they could have been otherwise. But
Descartes also holds that God created the possibility that they not be
necessary, and that is why they are not necessarily necessary, as it
could have been the case that they could have been otherwise. Some
commentators have argued that a problem for Curley's view is that it
cannot allow Descartes to hold that eternal truths are absolutely
necessary — if it could have been the case that a given truth
could have been otherwise then it is not a necessary
truth.[14]
Another problem is that Curley's view appears to put a severe
constraint on divine omnipotence: if God wants to make an eternal
truth false, He cannot make it false without first willing that it not
be necessary, for a necessary truth cannot be made false. If God
alters the status of the truth so that it is no longer a necessary
truth, He can make it false, but He cannot make it false
straightaway. A final problem is that Curley's reading supposes that
there is some point at which God's will could have been otherwise, but
God is eternal, and part of His essential perfection is to be wholly
immutable (Principles II:36, AT 8A:62).

An alternative reading of Descartes' comments on the eternal truths
suggests still another interpretation. Jonathan Bennett has pointed
out that in some of the key passages in question Descartes does not
say that God can make contradictories true but that we should not say
that God cannot make contradictories true (Bennett 1994, 653–55). In
such passages, for example in the already-cited 1648 letter to
Arnauld, Descartes is not saying anything about God's power but about
us and what we ought not say. Presumably, he is just invoking his
Fourth Meditation rule for judging in these passages, as he is very
explicit that when we do metaphysics we ought not affirm what we do
not clearly and distinctly
understand.[15]
Since we do not come close to
understanding what it would be for one and two to add up to something
other than three, and since we do not understand God's being unable to
do something, the prospect that God cannot make 1 and 2 not add to 3
is hopelessly confused. Accordingly, we ought not speak of it. The
same analysis also applies to the important passage in the Mesland
letter. Immediately after saying that God can make contradictories
true together, Descartes takes it back: “… even if this
be true, we should not try to comprehend it, since our nature is
incapable of doing so.” Descartes' claim that God can make
contradictories true is something that we ought not affirm when doing
metaphysics and thus something that should have no bearing on our
interpretation of Descartes' system. Perhaps Descartes' initial
comments (about God's power to make contradictories true) are just an
expression of faith and devotion, in an attempt to gesture at His
greatness and perfection. But his official reason for the retraction
is more telling. Descartes writes,

But if we would know the immensity of his power we should
not put these thoughts before our minds, nor should we conceive any
precedence or priority between his intellect and his will; for the
idea which we have of God teaches us that there is in him only a
single activity, entirely simple and entirely pure. (AT
4:119)

This claim also calls to mind the passage in the Third Meditation in
which Descartes says that in God there is absolutely nothing that is
potential (AT 7:47, CSM 2:32). If there is just a single activity in
God, and if it is simple and eternal, and also immutable, then it
makes no sense to talk of God as changing course and actualizing an
alternative set of possibilities aside from than the one that actually
obtains. There do not exist alternative possible eternal truths, and
there does not exist the possibility of a change in God's eternal and
immutable will, and so (contra Frankfurt et al) eternal truths are
absolutely necessary.

Another consideration to mention in favor of the view that Descartes
holds that eternal truths are absolutely necessary is that it is
sensitive to the important worry raised by Broughton (1987) and Nadler
(1987) — that Descartes should not say that physical laws follow
from God's nature and so are absolutely necessary, in a way that has
them admitting of more necessity than the truths of mathematics and
geometry. If anything, we would expect the story to go the other way
around — that eternal truths would be necessary and that physical
laws would be wholly contingent. In Descartes' system it would appear
that laws of physics are necessary and that eternal truths are
necessary as well.

Still we need to contend with the passage in which Descartes says that
God was free to make the radii of a circle unequal, and with the
passages in which Descartes says more generally that God is free with
respect to each and every thing that He does. One way to read these
passages is to make the assumption that Descartes has a libertarian
conception of divine freedom and then conclude that if Descartes says
that God is free to do something, there exists the possibility that He
do it and also the possibility that He do something else (perhaps the
opposite).[16]
Descartes himself appears to understand divine freedom in very
different terms. He writes,

As for the freedom of the will, the way in which it exists in God is
quite different from the way in which it exists in us. It is
self-contradictory to suppose that the will of God was not indifferent
from eternity with respect to everything that has happened or will
ever happen; for it is impossible to imagine that anything is thought
of in the divine intellect as good or true, or worthy of belief or
action or omission, prior to the decision of the divine will to make
it so. (Sixth Replies, AT 7:431–32, CSM 2:291)

Descartes holds that God is free in creating the eternal truth about
the radii of a circle. If God's freedom in this and other cases just
consists in His complete indifference and independence, then the
Cartesian claim that God is free do x does not entail that
there exists the possibility that God not do x or that there
exists the possibility that God do something else. As Descartes makes
very clear, such possibilities exist only if God takes the extra step
of creating them.

Descartes makes a number of otherwise puzzling claims about God's
freedom to create the eternal truths, but if we interpret these in the
light of Descartes' stated conception of divine freedom, they begin to
look fairly mundane. A problem, however, is that taken together the
claims encourage the reading that Descartes is a necessitarian. We
consider for example the following comment that Descartes makes to
Mersenne:

It will be said that if God had established these truths
he could change them as a king changes his laws. To this the answer
is: Yes he can, if his will can change. ‘But I understand them
to be eternal and unchangeable.’ — I make the same
judgment about God. ‘But his will is free.’ — Yes,
but his power is beyond our grasp. (“To Mersenne, 15 April
1630,” AT 1:145–46, CSMK 23).

Here Descartes allows that there exists the possibility that God
create alternate eternal truths only if God's will is mutable, but of
course Descartes holds that God's will is wholly immutable, and
immutable for eternity. God is still free of course, but in a way
that squares with His immutability: divine freedom is to be understood
in terms of indifference and independence. The worry that is starting
to arise is that if God is the immutable and eternal author of all
reality — the eternal truths and everything else that exists — then
there does not exist the possibility that God will an alternate series
of creatures, and hence God does not create that possibility, but
instead everything that happens happens necessarily. Descartes
subscribes to a version of the Spinozistic view that divine freedom is
a matter of
indifference,[17]
and there is now some systematic evidence
that Descartes accepts the Spinozistic doctrine of necessitarianism. As
Descartes recognizes in the 15 April 30 letter to Mersenne, we might
encounter some cognitive dissonance in recognizing God's
freedom as
omnipotence.[18]
He appears to subscribe to the view that
the eternal truths are necessary and that everything else that happens
is necessary as
well.[19]
As he is reported to have said
in Conversation with Burman:

Concerning ethics and religion,… the opinion has
prevailed that God can be altered, because of the prayers of mankind;
for no one would have prayed to God if he knew, or had convinced
himself, that God was unalterable…. From the metaphysical point
of view, however, it is quite unintelligible that God should be
anything but completely unalterable. It is irrelevant that the decrees
could have been separated from God; indeed, this should not really be
asserted. For although God is completely indifferent with respect to
all things, he necessarily made the decrees he did, since he
necessarily willed what was best, even though it was of his own will
that he did what was best. We should not make a separation here
between the necessity and the indifference that apply to God's
decrees; although his actions were completely indifferent, they were
also completely necessary. Then again, although we may conceive that
the decrees could have been separated from God, this is merely a token
procedure of our own reasoning: the distinction thus introduced
between God himself and his decrees is a mental, not a real one. In
reality the decrees could not have been separated from God: he is not
prior to them or distinct from them, nor could he have existed without
them. (AT 5:166, CSMK 348)

If Descartes holds in the final analysis that everything that happens
happens necessarily, it is easy to see how he can hold that eternal
truths are necessary and created by a God that is free (in the
Cartesian sense). However, Descartes will still have to contend with
the objection that there are texts in which he seems to be committed
to the existence of unactualized possibilities and, in particular,
texts in which he appears to be committed to a non-compatibilist view
of human freedom.[20]

Thus far we have considered the interpretive issue of whether or not
Descartes' eternal truths could have been otherwise. A question that
still remains to be considered concerns the ontological status of
Descartes' eternal truths, regardless of whether or not they could have
been otherwise.

One view is that since Descartes' eternal truths are neither finite
mental things, finite physical things, nor God, they must be something
akin to Platonic
forms.[21]
A problem with this view, of course, is
that it does violence to Descartes' parsimonious dualism. Another
problem with the view is that Descartes says that eternal truths are
beings which “have no existence outside our thought”
(Principles I:48, AT 8A:23, CSM 1:208).

A second view is that eternal truths are to be located in
God.[22]
One of the merits of this view is that it provides for eternal truths
to be eternal in a very robust sense. God is eternal, and anything
else is eternal if it is housed in His eternal mind. Still, the view
conflicts with the fact that Descartes holds that eternal truths are
creatures and are housed in finite minds.

A third reading of Descartes on eternal truths is that they are ideas
in finite minds. If truth is the conformity of thought with its object
(“To Mersenne, 16 October 1639,” AT 2:597, CSMK 139), then
eternal truths are ideas. But Descartes has also said that eternal
truths have no existence outside of our thought. They are true ideas,
but not true ideas in the mind of God because eternal truths are
creatures. A problem with this reading, however, is that, although it
allows eternal truths to be truths, it is not clear that it
allows them to be
eternal.[23]
In some passages
Descartes does distance himself from the appellation ‘eternal
truth’: he refers to “those truths which are called
eternal” (“To Mersenne, 27 May 1638,” AT 2:138, CSMK
103) and to “[t]he mathematical truths which you call
eternal” (To Mersenne, 15 April 1630, AT 1:145, CSMK 23). And
he allows that things can be identified as ‘eternal’ so
long as they “are always the same” (Fifth
Replies, AT 7:381, CSM 2:262). So a deflationary view of the
eternality of Cartesian eternal truths might be in order. However,
Descartes says to Mersenne that “from all eternity [God] willed
them [eternal truths] to be, and by that very fact he created
them” (“To [Mersenne], 27 May 1630,” AT 1:152, CSMK
25). Here Descartes appears to attribute to eternal truths an
eternality that they cannot have if they have no existence outside of
our thought.[24]
Perhaps a compromise interpretation would be that Descartes holds that
God has willed the series of creatures from eternity and that some of
these creatures are truths that are “always the same” once
created.

Descartes is unambiguous that there are some things that we clearly
and distinctly perceive to be possible. To Mersenne he speaks of
beings whose existence we clearly perceive to be possible (“To
Mersenne, March 1642,” AT 3:544–45, CSMK 211); he also says
that God “can bring about everything that I clearly and
distinctly recognize as possible” (Fourth Replies, AT
7:219, CSM 2:154). In First Replies he says that

…we must distinguish between possible and necessary
existence. It must be noted that possible existence is contained in
the concept or idea of everything that we clearly and distinctly
understand; but in no case is necessary existence so contained except
in the case of the idea of
God.[25]

In addition, he says to Mesland that “our mind is finite and
so created as to be able to perceive as possible things which God has
wished to be in fact
possible.”[26]
The interpretive issue
here is what Descartes is talking about when he speaks in such terms.
One interpretation that immediately suggests itself is that Descartes
holds that there are things or states of affairs that, though not
actual, are counterfactually
possible.[27]
A number of
considerations speak in favor of such a reading. One is that Descartes'
view that mind and body are really distinct appears to be the view that
minds and bodies that are in fact united can exist
apart.[28]
Another is
that Descartes says that we have clear and distinct perceptions of
possible existence and of what is possible, thus making it appear that
he holds that God's creatures include not only actuals but also
unactualized
possibles.[29]
Finally, this sort of reading fits Descartes
within a long tradition of figures like Scotus and Brandwardine who
posit possible being to secure the meaning and reference of claims
about things that could be but
aren't.[30]
If Descartes wants to
make claims about unactualized possibles and if he does not want those
claims to be non-sensical, unactualized possibles need to have some
kind of ontological status in his system.

Descartes may in fact be committed to attributing reality to
unactualized possibles, but a few interpretive problems arise if he
does. One is that Descartes says elsewhere that unactualized being is
nothing. In the Third Meditation, he argues that the objective reality
of the idea of God cannot have been caused by potential perfections
towards which a finite being might be evolving because potentialities
are nothing and so have no causal power. He says,

… I perceive that the objective being of an idea cannot
be produced merely by potential being, which strictly speaking is
nothing, but only by actual or formal being. (AT 7:47, CSM
2:32)

If Descartes holds that potential being is nothing, then it is
difficult to see how he can include unactualized possibles in his
ontology.

Another interpretive problem is that it is difficult to see exactly
where possible reality would fit into Descartes' ontology. For
Descartes, all reality depends for its existence on God — even
possible reality (“To [Mesland], 2 May 1644,” AT 4:118–9,
CSMK 235). A possible being is thus a creature with an ontological
status. Descartes holds that truth is the conformity
of thought with its object, that “[t]ruth consists in being”
(“To Clerselier, 23 April 1649,” AT 5:356, CSMK 377), and
that true ideas are “ideas of real things” (The Third
Meditation, AT 7:43, CSM 2:30). Clear and distinct perceptions of
possibilities conform to reality and are of real things; they have a
truth-maker. A clearly and distinctly perceived possibility has some
ontological status, and the question is what exactly that is. This is
a question on which the Descartes literature has been largely silent,
but the options would appear to be that possibilities are either
creatures or ideas in the mind of God.

If possible beings are creatures, there is some difficulty in making
room for them in Descartes' ontology. Descartes is fairly clear that
the only creatures that exist are finite minds and bodies and their
modes:

I recognize only two ultimate classes of things: first, intellectual
of thinking things, i.e. those which pertain to mind or thinking
substance; and secondly, material things, i.e. those which pertain to
extended substance or body. Perception, volition and all the modes
both of perceiving and willing are referred to thinking substance;
while to extended substance belong size (that is, extension in length,
breadth and depth), shape, motion, position, divisibility of component
parts and the
like.[31]

One category of being in Descartes' ontology is thinking substance
(and its modes), and another is extended substance (and its modes). If
Descartes' possibles are just created thinking or extended substances,
then presumably they are actuals and not possibles.

Of course, one might suggest that Descartes' dualism entails that
there are two kinds of things — thinking things and material things
-- but that in each of these classes there are substances with actual
existence and also substances with possible existence. On such a view,
the class of thinking substances (for example) includes thinking
substances with actual existence and thinking substances with possible
existence.

There are a couple of problems with this view, however. One is that
Descartes holds that it follows from God's essence that God is eternal
and that His will is wholly immutable (The Third Meditation, AT 7:45,
CSM 2:31; Principles I:56, AT 8A:26, CSM 1:211; “To
Mersenne, 15 April 1630,” AT 1:145–6, CSMK 23;
Principles II:36, AT 8A:61, CSM 1:24). If it is a necessary
truth that God is eternal and that His will is immutable, then there
does not exist the possibility that God's eternal will could have been
other than it is. So that possibility does not exist; and neither
does it appear that there exist any possible creatures. Descartes
holds that there is a single series that God preordains and that is
(as would be expected) immutable (Principles I:40–41, AT
8A:20, CSM 1:206). If God created things that were merely possible,
it is unclear how He would be able to actualize them instead of the
things that are actualized in the series, if none of the requisite
possibilities exist, and so it is unclear how they would
constitute possibilities. These alleged possibilities (if
they are anything) would be among all of the other creatures; they
would be actuals.

It might of course be the case that Descartes just insists that there
are possible existents in addition to actual existents. Alternately,
it might be the case that like Spinoza (in Ethics Part IV,
definitions three and four), Descartes uses the expression
“possible existence” to describe actually-existing
creatures, and in a way that is consistent with a denial of non-actual
reality. For example, in some places Descartes identifies things as
having possible existence to highlight that they are dependent
creatures, and creatures whose existence cannot be read straight from
their concept. To describe the kind of existence had by finite
creatures generally, he uses ‘possible existence’ and
‘contingent existence’ interchangeably: he sometimes
speaks of the beings that depend on God for their existence as having
“possible or contingent existence” (Second
Replies, AT 7:166, CSM 2:117; Notae, AT 8B:361, CSM
1:306), and sometimes he speaks of them as having just
“contingent existence” (Principles I:15, AT
8A:10, CSM 1:198). When he says that creatures have
possible or contingent existence, he identifies the two kinds
of existence: “possible or [vel] contingent
existence.” If contingent existence is just the kind of
existence had by beings that depend for their existence on God's will
and whose existence cannot be established by an analysis of their
concept alone (Fifth Meditation, AT 7:63–66, CSM 2:44–46; Rules
for the Direction of the Mind, AT 10:421–22, CSM 1:45–46), then
the fact that a thing has possible existence in Descartes' ontology
does not suggest that the thing does not actually exist. Such a thing
exists, but in a way that has it wholly dependent on God. Descartes
also suggests this definition of “possible existence” when
he contrasts necessary existence with the kind of existence had by
creatures in First Replies: unlike necessary existence, the
existence had by a creature is marked by the fact that it “has
no power to create itself or maintain itself in existence” (AT
7:118, CSM 2:84). It might be that like some of his predecessors
Descartes is using ‘possible existence’ to describe a kind
of being had by actually existing
things.[32]

If possibilities are not creatures that exist in addition to thinking
substances and extended substances, another interpretive option is to
say that they are ideas in the mind of God, but that God does not
actualize. This interpretive option is precluded by Descartes'
commitment to the identity of God's will, intellect, and creative
activity:

…in God, willing, understanding, and creating are
all the same thing without one being prior to the other even
conceptually. (“To Mersenne, 27 May 1630,” AT 1:152, CSMK
25–26)

In God willing and knowing are a single thing in such a
way that by the very fact of willing something he knows it and it is
only for this reason that such a thing is true. (“To Mersenne, 6
May 1630,” AT 1:149, CSMK 24)

A philosopher like Leibniz will insist on a distinction between God's
understanding and will so as to secure the existence of things in
God's understanding that God does not actually create. A philosopher
like Spinoza will point out that a thinker who is committed to the
identity of God's will and intellect is committed to the view that
there is nothing that God understands that God does not create.
Spinoza will add that such a thinker is not restricting God's
omnipotence if God is the cause of all being and if alleged
unactualized possibilities are outside the scope of God's intellect
and will. Descartes appears to be siding with Spinoza here: what is
not the object of God's understanding is nothing at all, and
what is the object of God's understanding is created and made
actual.[33]
If Descartes is seriously committed to the identity of God's
intellect and will, it is difficult to see how he can also be
committed to the existence of unactualized possibles.

There are a number of passages in which Descartes speaks of what is
possible. To fix an interpretation of these passages, we can look to a
number of different places. One is common-sense. We might argue that
any view is crazy that does not admit that there are things that could
happen or exist but that do not. Since Descartes is not crazy, what he
must mean when he speaks of the possible is unactualized being. Or, we
might argue that Descartes is continuing in the tradition of thinkers
who clearly do posit unactualized possibles. If these figures
include unactualized being within their ontologies, and if Descartes
is building on their work, then his claims about the possible are
about unactualized being. Or, we might attempt to isolate parts of
Descartes' system that have a bearing on what “possible”
might mean in his system. Parts of this system entail that
‘possible existence’ is just the actual existence of
dependent beings. If by “possible existence” Descartes
just means the dependent existence of actually existing creatures,
then passages in which Descartes speaks of a thing as being possible
or having possible existence are not evidence that Descartes holds
that there are things that could be but are not. Of course, it might
just be the case that Descartes has reason to help himself to entities
that the rest of his system shuts out.

If Descartes does hold that there are things that could be but are
not, his view still demands the important qualification discussed in
the first section above. He of course realizes that in everyday
discourse we speak of things that can happen but don't. However, if
our understanding of these things is not clear and distinct, and if
our understanding of them as possible is not clear and distinct, then
Descartes will not introduce them as possibilities. Descartes
appreciates that according to common ways of speaking, all kinds of
things are possible. He considers this concept of
‘possible’ after Mersenne introduces it in Second
Objections:

If by ‘possible’ you mean what everyone
commonly means, namely ‘whatever does not conflict with our
human concepts’, then it is manifest that the nature of God, as
I have described it, is possible in this sense…. (Second
Replies, AT 7:150, CSM 2:107)

Here Descartes might seem to be offering a theory of possibility
according to which what it means for something to be possible is just
for it to be
conceivable.[34]
However, this cannot be Descartes' view. Descartes holds that
whatever we clearly and distinctly perceive is true and that truth is
“the conformity of thought with its object” (“To
Mersenne, 16 October 1639,” AT 2:597, CSMK 139). If a
possibility that we are considering is clearly and distinctly
perceived, then our clear and distinct perception conforms to reality,
and the possibility that we are conceiving is not merely conceptual.
Instead, there is also an object to which the clear and distinct
perception conforms — the sort of thing posited by commentators who
argue that Descartes holds that God's creation consists not only of
actuals but of unactualized possibles. Thus, for any possibility of
which we have a conception, if there is no object to which that
conception conforms — that is, if the possibility exists
only in thought — the possibility is not clearly and
distinctly perceived. Possibilities which exist only in
thought are not part of Descartes' ontology and so on Descartes' view
are not possibilities at all. Descartes' remarks to Mersenne actually
bear this out. He is indeed considering the view of possibility as
conceivability, but in doing so he is merely acknowledging what
“everyone commonly means” by
‘possible’. Descartes sometimes speaks of the possible as
clearly and distinctly perceived. It is on these passages that any
interpretation of Descartes' views on possibility must be built.

Any interpretation of Descartes' views on modality needs to be
sensitive to his view that mind and body are really distinct. The
conclusion of his Sixth Meditation argument for substance dualism is
that “I am really distinct from my body, and can exist without
it” (AT 7:78, CSM 2:54). A natural reading of Descartes'
conclusion has him saying that, for any minds and bodies that are
united, it is counterfactually possible that they be
separated.[35]
His
argument would be as follows:

I clearly and distinctly understand mind apart from body and body
apart from mind.

God can bring about whatever I clearly and distinctly
perceive.

God can bring about that mind is apart from body and body is apart
from mind.

If God can bring about that mind is apart from body and body is
apart from mind, then mind and body can exist apart.

Mind and body can exist apart.

Such a reading is sensitive not only to Descartes' Sixth Meditation
comments but also to his further remarks on real distinction in Fourth
Replies. There Descartes says that for “establishing a real
distinction it is sufficient that two things can be understood as
‘complete’ and that each one can be understood apart from
the other” (AT 7:221, CSM 2:156). A thing is complete, for
Descartes, when it is a substance:

… [B]y a ‘complete thing’ I simply mean
a substance endowed with the forms or attributes which enable me to
recognize that it is a substance. (AT 7:222, CSM 2:156)

Since a Cartesian substance is a thing that is ontologically
independent (Principles I:51–52), a complete thing is an
ontologically independent thing. When we clearly and distinctly
perceive mind and body to be complete, we know that they are
substances. When we still clearly and distinctly perceive them to be
substances after clearly and distinctly perceiving them apart from each
other, we know that they are not the same substance under different
descriptions. On this view, Descartes holds that mind and body are
ontologically independent substances, and their distinctness consists
in their ability to continue to exist even after God separates
them.[36]

An alternative interpretation of Descartes on the real distinction
between mind and body reads the distinction as consisting in the
ontological independence of mind and body, but not in their
separability.[37]
Descartes holds that a sufficient condition for establishing a real
distinction between two things is clearly and distinctly perceiving
them to be non-identical substances (“Synopsis of these
following six Meditations,” AT 7:13, CSM 2:9; Fourth
Replies, AT 7:221–223, CSM 2:156–58). If so, he holds that
the substantiality of two non-identical substances does not consist in
their being separable but is just an indication of their
separability.[38]
On this view, mind and body are separable
for Descartes; it's just that their separability is a consequence of
the (different) fact that they are really
distinct.[39]

A third reading of the Cartesian real distinction stresses the
difficulty in making room for unactualized possibilities in Descartes'
system. The reading also highlights that Descartes holds that our
clear and distinct perceptions are veridical but says (in his proof of
real distinction) that God can bring about whatever we
clearly and distinctly perceive. Descartes is clear in other texts
that the reason why he mentions God's power in the proof of real
distinction is to remind us that no matter how unlikely we think it is
that our intimately united minds and bodies could also be really
distinct, God has enough power to have made all of our clear
and distinct perceptions veridical:

You agree that thought is an attribute of a substance
which contains no extension, and conversely that extension is an
attribute of a substance that contains no thought. So you must also
agree that a thinking substance is distinct from an extended
substance. For the only criterion we have enabling us to know that
one substance differs from another is that we understand one apart
from the other. And God can surely bring about whatever we can
clearly understand; the only things that are said to be impossible for
God to do are those which involve a conceptual contradiction, that is,
which are not intelligible. But we can clearly understand a thinking
substance that is not extended, and an extended substance that does
not think, as you
agree.[40]

In Fourth Replies Descartes say that his reason for
mentioning God's power in the Sixth Meditation proof of real
distinction is to remind his reader that our clear and distinct
perceptions are veridical (AT 7:226, CSM 2:159). In the Sixth
Meditation itself he arrives at a clear and distinct perception of
mind as an immaterial substance and body as a material non-thinking
substance and is immediately struck by the union of his mind and body:
“It is true that I may have… a body that is very closely
joined to me” (AT 7:78, CSM 2:54). He says that “nevertheless”
his mind and body are really distinct. Descartes appreciates that the
facts of mind-body union and mind-body separation are
opposed.[41]
In the context of demonstrating the real distinction between mind and
body he reminds us that God's power is such that there can be
creatures that have nothing in common but that are intimately
united.[42]

If we take seriously the consideration that there is no room in
Descartes' ontology for unactualized possibilities, the real
distinction between mind and body does not amount to their
counterfactual
separation.[43]
God has willed the series of creatures from eternity, and the claim
that mind and body can exist apart might amount to the claim that when
a given mind and body are separated in the series, each is
ontologically independent and so continues to
exist.[44]
That is, instead of
reflecting that there is anything more in Descartes' ontology than
what is contained in the series that God wills and preordains, the
claim that mind and body can exist apart might amount to Descartes'
note in “Synopsis of these following six Meditations” that
in the Sixth Meditation he is attempting to re-assure us that “the
decay of the body does not imply the destruction of them mind” (AT
7:13, CSM 1:10).

If Descartes holds that potential being is strictly speaking nothing,
and if his ontology and his commitment to divine immutability, divine
preordination, and (his particular conception of) omnipotence bar
possibilities from his system, it is not exactly clear what to make of
the possibility of mind and body existing in separation. One view is
that Descartes is committed to the reality of this possibility and
that, with his commitment to other possibilities, this commitment is
part of a pattern of Descartes' helping himself to entities that his
system does not allow. That is, it might be the case that Descartes
wants his system to be rich enough to posit possibilities and that,
when it isn't, he posits them anyway. Or, it might be the case that
because the Meditations does not attempt to analyze (and then
refine) the meditator's pre-Meditations view of modality, the
‘can’ in Descartes' claim that mind and body can exist apart is the
not fully analyzed ‘can’ of the
vernacular.[45]

The whole project of the Fourth Meditation would appear to suggest
that Descartes is committed to the view that human beings can do
something other than what God preordains. The Fourth Meditation tells
us that error is avoidable, that we err not as as a result of the way
that we are constructed but as a result of our mis-use of one of the
faculties that God has provided us, and that to avoid error we must
refrain from affirming what we do not perceive clearly and
distinctly.

But there are passages in Descartes' corpus that make a surface
reading of the Fourth Meditation problematic. One is of course
the Principles I:40–41 text in which Descartes says that God
pre-ordains everything from eternity. He does admit that “we
can easily get ourselves into great difficulties if we attempt to
reconcile this divine preordination with the freedom of our will, or
attempt to grasp both these things at once” (AT 8A:20, CSM
1:206). But this just means that he himself appreciates the
problem.

There are other difficult texts as well:

…[P]hilosophy by itself is able to discover that the
slightest thought could not enter a person's mind without God's
willing, and having willed from all eternity, that it should so
enter. ...When Your Highness speaks of the particular providence of
God as being the foundation of theology, I do not think that you have
in mind some change in God's decrees occasioned by actions that depend
on our free will. No such change is theologically tenable; and when
we are told to pray to God, that is not so that we should inform him
of our needs, or that we should try to get him to change anything in
the order established from all eternity by his providence...[,] but
simply to obtain whatever he has from all eternity, willed to be
obtained by our prayers. (“To Princess Elisabeth, 6 October
1645,” AT 4:314–6, CSMK 272–73)

As for free will, I agree that if we think only of
ourselves we cannot help regarding ourselves as independent; but when
we think of the infinite power of God, we cannot help believing that
all things depend on him, and hence that our free will is not exempt
from this dependence. … The independence which we experience and feel
in ourselves, and which suffices to make our actions praiseworthy or
blameworthy, is not incompatible with a dependence of quite another
kind, whereby all things are subject to God. (“To Princess
Elisabeth, 3 November 1645,” AT 4:332–3, CSMK 277)

Henceforth, because he [the man who meditates upon God]
knows that nothing can befall him which God has not decreed, he no
longer fears death, pain or disgrace. He so loves this divine decree,
deems it so just and so necessary, and knows that he must be so
completely subject to it that even when he expects it to bring death
or some other evil, he would not will to change it even if, per
impossible, he could do so. (“To Chanut, 1 February
1647,” AT 4:609, CSMK 310)

In the Principles I:40–41 discussion, Descartes appeals to
divine incomprehensibility to make sense of how human freedom and
divine preordination are to be reconciled. God is infinitely
powerful, and He somehow made a universe in which it is true both that
human beings are free and that God has preordained everything from
eternity (AT 8A:20, CSM 1:206). Perhaps we should just assume that
Descartes thinks that human freedom is inconsistent with divine
pre-ordination and that we cannot make sense of human freedom (except
by appeal to divine incomprehensibility).

Another interpretive option is to emphasize that
in Principles 1:40–41 Descartes is saying only that our
experience of freedom and independence is in tension with divine
pre-ordination (Cunning 2010, 138-42). There is a way in which our
experience of freedom is perfectly consistent with divine
pre-ordination, of course, if God has immutably decreed all of our
mental life for all eternity and if our mental life includes some
experiences and not others. But it might seem puzzling why we have an
experience of freedom at all. Still, if Descartes allows that human
freedom itself is consistent with divine pre-ordination, then he is
not a libertarian but a compatibilist.

Passages outside of the Meditations might be easily read
as consistent with the view that for Descartes there does not exist
any unactualized possible reality, but the view appears not to square
with many of the claims of the Fourth Meditation. The Meditation does
contain compatibilist-sounding claims -- for example, that the will is
maximally free when it is compelled to affirm truth (AT 7:58, CSM
2:40); that it would be impossible for us to be in a state of
indifference if we had distinct perceptions only (ibid.); and that
assent and dissent are a matter of the will being pulled and compelled
by reasons (AT 7:59; CSM 2:41). However, the whole point of the
Fourth Meditation would seem to be that God is imperfect if our errors
(and false affirmations) are inevitable, and thus that on any given
occasion it is always possible for us to affirm or deny. A
compatibilist reading of the Fourth Meditation resolution of the
problem of error has to emphasize the following (Cunning 2010, chapter
five): that much of the Fourth Meditation is fully compatibilist; that
the Meditation provides reasons that push and compel the will to
refrain from affirming perceptions that are not clear and distinct;
that the Meditation provides reasons that compel the will to affirm
that whatever we perceive to be fully evident is true; that Descartes
insists that upon further reflection (that occurs beyond
the Meditations) it is clear that the entirety of our mental
lives depends on God's eternal and immutable will and that, as a
result, nothing that happens (including pain and death, and presumably
error) is bad; that something (like error) can be the outcome of God's
will even if God does not will it directly; and that Descartes' Fourth
Meditation meditator is not yet a full-blown Cartesian.

A final issue to consider in the context of discussing Descartes' view
on human freedom is the issue of the extent to which finite minds are
compelled or drawn to affirm clear and distinct perceptions. There
are a number of texts in which Descartes reflects that view that
finite minds are wholly unable to refrain from affirming a clear and
distinct
perception.[46]
Indeed, we might think that the only way that we would be able to
know that God's non-deceiverhood secures the truth of clear and
distinct perceptions is if those perceptions are utterly compelled.
There are passages, however, in which Descartes appears to reflect the
view that it is within the power of the will to refrain from affirming
a clear and distinct perception. One is Principles I:37, in
which Descartes says that “when we embrace the truth, our doing
so voluntarily is much more to our credit than would be the case if we
could not do otherwise” (AT 8A:19, CSM 1:205). But this passage
is especially odd given that only a few lines later in Principles I:43
Descartes offers one of his statements of the view that we are unable
to doubt clear and distinct perceptions (in which we are embracing the
truth…).[47]

Another passage in which Descartes appears to reflect the view that it
is within the power of a finite will to refrain from affirming a clear
and distinct perception is in “To [Mesland], 9 February
1645.” There Descartes writes that

absolutely speaking… it is always open to us to
hold back from pursuing a clearly known good, or from admitting a
clearly perceived truth, provided we consider it a good thing to
demonstrate the freedom of our will by so doing. (AT 4:173, CSMK 245)

An examination of the larger context of this passage in the shows that
it is not in fact evidence that Descartes holds that it is within the
power of a finite will to refrain from affirming a clear and distinct
perception. In the previous letter to Mesland Descartes had said
that

I agree with you when you say that we can suspend our
judgment; but I tried to explain in what manner this can be done. For
it seems to me certain that a great light in the intellect is followed
by a great inclination in the will; so that if we see very clearly
that a thing is good for us, it is very difficult — and on my
view impossible, as long as one continues in the same thought —
to stop the course of our desire. “To [Mesland], 2 May
1644,” AT 4:115–6, CSMK 233)

Descartes' view that clear and distinct perceptions are
will-compelling is the view that so long as the intellect has a clear
and distinct idea, it is impossible for the will to refrain from
affirming it. What it is for a finite mind to clearly and distinctly
perceive X is for its intellect to have a clear and distinct idea
of X
and for its will to affirm X, but while the intellect is presenting
this clear and distinct idea, the will cannot stop affirming it to
turn its attention to something else. Instead, another idea must be
put in place of the clear and distinct idea, and by something other
than the
will.[48]
As Descartes says by way of qualification in the February 1645
letter, we suspend judgment when something else distracts the will
from a clear and distinct idea (AT 4:173, CSMK 245) — for
example the desire to exhibit our
freedom.[49]

It is tempting to assume that Descartes accepts the Spinozistic view
that the will is at the mercy of the clarity with which the intellect
has ideas. (Of course, in Spinoza's language the view is that there
is no distinction between will and intellect and that to the extent
that we understand something our will is drawn to affirm it.)
Descartes appears to accept this view in the case of clear and
distinct ideas at least, and it would make sense for him to think that
the compellingness of truth and goodness does not disappear when our
grasp of it is slightly weakened. But such a reading is speculative
at best.

It is presumably an adequacy condition on the interpretation of the
work of any systematic philosopher that the work be interpreted in
light of the central tenets of that philosopher's system. The
interpretive problem of course is that for almost any such philosopher
there are controversies about what these central tenets are. It is
uncontroversial that Descartes sometimes speaks of possibility and
necessity. What is not so uncontroversial is what he is talking about
when he talks about these. In particular, if Descartes is committed to
the view that there is unactualized possible being, then either (1)
the alleged parts of his system that seem to disallow such being are
not parts of his system, (2) the parts of his system that seem to
disallow such being do not really disallow it, or (3) he is not a
wholly systematic philosopher.

–––, 2008, “Descartes' Ontology of the
Eternal Truths,” in Paul Hoffman, David Owen and Gideon
Yaffe, Contemporary Perspectives on Early Modern Philosophy:
Essays in Honor of Vere Chappell, London: Broadview Press.